系统环境
Centos8
现有的文件系统
下面使用了/dev/sd[a-c]三块磁盘，将他们划入一个卷组，创建两个逻辑卷：
# Create pv[root@localhost ~]# pvcreate /dev/sda[root@localhost ~]# pvcreate /dev/sdb[root@localhost ~]# pvcreate /dev/sdc# Create VG[root@localhost ~]# vgcreate vg_data /dev/sd[a-c]# Create LV[root@localhost ~]# lvcreate -L 25G -n lv_data vg_data[root@localhost ~]# lvcreate -L 25G -n lv_log vg_data
下面列出逻辑卷的分配使用信息：
[root@localhost ~]# pvs PV VG Fmt Attr PSize PFree
/dev/nvme0n1p2 cl lvm2 a-- # vgs
VG #PV #LV #SN Attr VSize VFree cl 1 2 0 wz--n- # lvs -a -o +devices
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert Devices
root cl -wi-ao---- 15.00g /dev/nvme0n1p2(512)
swap cl -wi-ao---- 2.00g /dev/nvme0n1p2(0)
lv_data vg_data -wi-a----- 25.00g /dev/sda(0)
lv_data vg_data -wi-a----- 25.00g /dev/sdb(0)
lv_log vg_data -wi-a----- 25.00g /dev/sdc(0)
lv_log vg_data -wi-a----- 25.00g /dev/sdb(1281)
在根目录创建两个文件夹/data和/log，格式化逻辑卷，挂载逻辑卷，并存放一些数据：
[root@localhost ~]# mkdir /data /logs[root@localhost ~]# mkfs.xfs /dev/vg_data/lv_data[root@localhost ~]# mkfs.xfs /dev/vg_data/lv_log[root@localhost ~]# mount /dev/vg_data/lv_data /data[root@localhost ~]# mount /dev/vg_data/lv_log /data[root@localhost ~]# df -hFilesystem Size Used Avail Use% Mounted on
devtmpfs 880M 0 880M 0% /dev
tmpfs 897M 0 897M 0% /dev/shm
tmpfs 897M 8.7M 888M 1% /run
tmpfs 897M 0 897M 0% /sys/fs/cgroup
/dev/mapper/cl-root 15G 1.9G 14G 13% /
/dev/nvme0n1p1 976M 183M 726M 21% /boot
tmpfs 180M 0 180M 0% /run/user/0
/dev/mapper/vg_data-lv_log 25G 211M 25G 1% /data
[root@localhost ~]# touch /data/file{1..10}.txt[root@localhost ~]# touch /logs/text{1..10}.log将磁盘设置为故障或删除磁盘
这两种情况是意外删除的物理卷或发生故障的磁盘，通过运行pvremove命令删除了任何一个物理卷，或者从虚拟机中移除某一块物理磁盘。
下面从虚拟机中移除一块物理磁盘：
重启系统之后，发现不能挂载lv_data和lv_log逻辑卷了，/dev目录中找不到vg_data卷组。
如果该逻辑卷设置为开机自动启动了，磁盘发生故障后，由于两个逻辑卷无法挂载文件系统，因此重新引导不能进入系统。只能通过进入单用户模式，并注释fstab配置文件里面和该逻辑卷相关的条目。
添加新物理硬盘
下面从虚拟机中添加一个新的物理磁盘，新添加的磁盘会变成/dev/sdc
[root@localhost ~]# lsblk -SNAME HCTL TYPE VENDOR MODEL REV TRAN
sda 6:0:0:0 disk VMware, VMware Virtual S 1.0 spi
sdb 6:0:2:0 disk VMware, VMware Virtual S 1.0 spi
sdc 6:0:3:0 disk VMware, VMware Virtual S 1.0 spi
sr0 3:0:0:0 rom NECVMWar VMware SATA CD01 1.00 sata
恢复已删除物理卷的元数据
现在让我们开始为已删除的物理卷恢复元数据。当使用pvs,vgs,lvs命令时，它将警告缺少xxxxx UUID的设备之一。 
只需复制UUID并使用grep查看存档和备份。在进行重新引导之前，报告的UUID指的是/dev/sdb设备。
[root@localhost ~]# cat /etc/lvm/archive/vg_data_00002-1587647360.vg |grep -B 2 -A 9 "v6wYGZ-0dGA-8ecB-kec8-r2zv-gCJi-gulSAD"pv1 {
id = "v6wYGZ-0dGA-8ecB-kec8-r2zv-gCJi-gulSAD"device = "/dev/sdb" # Hint onlystatus = ["ALLOCATABLE"]
flags = []
dev_size = 41943040 # 20 Gigabytespe_start = 2048
pe_count = 5119 # 19.9961 Gigabytes}
[root@localhost ~]# cat /etc/lvm/backup/vg_data |grep -B 2 -A 9 "v6wYGZ-0dGA-8ecB-kec8-r2zv-gCJi-gulSAD"pv1 {
id = "v6wYGZ-0dGA-8ecB-kec8-r2zv-gCJi-gulSAD"device = "/dev/sdb" # Hint onlystatus = ["ALLOCATABLE"]
flags = []
dev_size = 41943040 # 20 Gigabytespe_start = 2048
pe_count = 5119 # 19.9961 Gigabytes}
让我们先使用pvcreate --test进行试运行：
[root@localhost ~]# pvcreate --test --uuid "v6wYGZ-0dGA-8ecB-kec8-r2zv-gCJi-gulSAD" --restorefile /etc/lvm/archive/vg_data_00002-1587647360.vg /dev/sdc TEST MODE: Metadata will NOT be updated and volumes will not be (de)activated.
Couldn't find device with uuid l5rSrt-SRfc-KQNw-Tm29-gx4D-ihBw-Xzum3L.
Couldn't find device with uuid v6wYGZ-0dGA-8ecB-kec8-r2zv-gCJi-gulSAD.
Couldn't find device with uuid UYyDyH-vc6D-XbQ7-ga1X-DKeM-ObLe-tdBLxR.
Physical volume "/dev/sdc" successfully created.
- –uuid 用于指定新创建的物理卷的uuid值。如果没有此选项，将生成随机UUID。在本实验中指定的uuid值是之前删除物理卷的uuid值。
- –restorefile 读取由vgcfgbackup生成的存档文件
去掉--test选项，正式创建物理卷：
[root@localhost ~]# pvcreate --uuid "v6wYGZ-0dGA-8ecB-kec8-r2zv-gCJi-gulSAD" --restorefile /etc/lvm/archive/vg_data_00002-1587647360.vg /dev/sdc Couldn't find device with uuid l5rSrt-SRfc-KQNw-Tm29-gx4D-ihBw-Xzum3L.
Couldn't find device with uuid v6wYGZ-0dGA-8ecB-kec8-r2zv-gCJi-gulSAD.
Couldn't find device with uuid UYyDyH-vc6D-XbQ7-ga1X-DKeM-ObLe-tdBLxR.
Physical volume "/dev/sdc" successfully created.
[root@localhost ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/nvme0n1p2 cl lvm2 a--
恢复卷组
然后使用lvm的备份还原卷组。首先加入--test试运行一下：
[root@localhost ~]# vgcfgrestore --test -f /etc/lvm/backup/vg_data vg_data TEST MODE: Metadata will NOT be updated and volumes will not be (de)activated.
Volume group vg_data has active volume: lv_log.
Volume group vg_data has active volume: lv_data.
WARNING: Found 2 active volume(s) in volume group "vg_data".
Restoring VG with active LVs, may cause mismatch with its metadata.
Do you really want to proceed with restore of volume group "vg_data", while 2 volume(s) are active? [y/n]: y
Restored volume group vg_data.
下面正式运行一下，去掉--test选项：
[root@localhost ~]# vgcfgrestore -f /etc/lvm/backup/vg_data vg_data Volume group vg_data has active volume: lv_log.
Volume group vg_data has active volume: lv_data.
WARNING: Found 2 active volume(s) in volume group "vg_data".
Restoring VG with active LVs, may cause mismatch with its metadata.
Do you really want to proceed with restore of volume group "vg_data", while 2 volume(s) are active? [y/n]: y
Restored volume group vg_data.
如果卷组和逻辑卷未激活，请使用下面命令激活：
# 扫描卷组[root@localhost ~]# vgscan Reading all physical volumes. This may take a while...
Found volume group "cl" using metadata type lvm2
Found volume group "vg_data" using metadata type lvm2# 激活卷组vg_data[root@localhost ~]# vgchange -ay vg_data 2 logical volume(s) in volume group "vg_data" now active# 扫描逻辑卷[root@localhost ~]# lvscan ACTIVE '/dev/cl/swap' [2.00 GiB] inherit
ACTIVE '/dev/cl/root' [15.00 GiB] inherit
ACTIVE '/dev/vg_data/lv_data' [25.00 GiB] inherit
ACTIVE '/dev/vg_data/lv_log' [25.00 GiB] inherit
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